It's generally not advisable to use a power supply with a voltage higher than 9 volts for Arduino boards. Doing so can damage the device or components. Genuine Arduino boards can be supplied by up to 15 volt power supply. But it’s better not to use adapter with voltage more than 12v for both original and clone Arduino boards.

Cheap power supply adapters typically have lower build quality, fewer safety features (such as over voltage, over current, and short circuit protection), less accurate voltage regulation, and lower efficiency. Expensive power supply adapters, on the other hand, offer better construction, precise regulation, enhanced safety features, and higher efficiency.

Also cheap power supply may lack effective electromagnetic interference (EMI), potentially causing signal interference in sensitive electronic circuits.

In summary, while inexpensive power supply adapters can be suitable for most applications, more expensive options typically offer superior build quality, performance, safety features, and additional functionalities. The choice depends on the specific requirements of your electronic devices and the importance of reliability and safety in your application. You can choose a suitable power supply for your project in this page.

You can use various types of power supply for your Arduino boards. It includes switching power supply, AC to DC power supply modules, and also power bank modules. The choice between these power supplies depends on your need of power (Watt) on output, safety features and other specs such as portability.

When choosing an adapter, there are several key points to consider to ensure compatibility, safety, and optimal performance. Here's a list of things to pay attention to:

• Voltage: Ensure that the adapter's output voltage matches the voltage requirements of the device you're powering.
• Current Rating (Amperage): The adapter's current rating should meet or exceed the device's current requirements. Having a higher current rating is generally safe.
• Connector Type and Size: Verify that the adapter's connector type and size match the input port of the device. Using an incompatible connector can lead to poor connections.
• Efficiency: Higher efficiency means less wasted energy and can be important for applications where power consumption is a concern.
• Voltage Input Range: Check the adapter's voltage input range to ensure it can handle the electrical specifications of the power outlets in your location.
• Cost: While cost is a consideration, prioritize the compatibility, safety, and reliability of the adapter over choosing the cheapest option.